Patent publications in the general field of this invention include the following:    US20010050757;    US20020075136;    US20020080245;    US20070127093;    US20080094515;    US20080170031;    US20080186707;    US20090201309;    US20090267876;    US20100007599;    US20100118008;    U.S. Pat. No. 7,158,673;    U.S. Pat. No. 6,989,859;    U.S. Pat. No. 5,276,779; and    JP2002092655.
The creator of a video production or other image (for example a director, colorist, or the like) may set tones and colors of pixels in the image so that, when viewed, the image has a desired appearance which agrees with the creator's creative intent. For example, a creator may wish some scenes to have a darker, more oppressive, feel than others. The creator may wish certain features depicted in a scene to stand out or to be less prominent. Adjusting tones and colors of pixels in an image may include performing color grading (or ‘color timing’) on the source video data. Color grading may be performed using a hardware/software system that permits a user to change the video data in various ways to achieve a desired appearance.
Various display technologies are now available. For example, there are plasma displays, LCD displays backlit by a variety of types of light sources such as LEDs of various types, fluorescent lamps or high-intensity incandescent lamps, CRT-based displays, digital cinema displays, etc. A particular display combines display hardware with video signal processing components that receive video signals and drive display hardware to display video content of the video signals.
Different displays may vary significantly with respect to features such as:
the color gamut that can be reproduced by the display;
the maximum brightness achievable;
contrast ratio;
resolution;
acceptable input signal formats;
color depth;
white level;
black level;
white point;
grey steps;
etc.
Consequently, the same image content may appear different when played back on different displays. Image content that matches a creator's creative intent when displayed on some displays may depart from the creator's creative intent in one or more ways when viewed on other displays.
Some current displays can outperform displays that were state-of-the-art at a time when certain content was created in one or more aspects. For example, new displays may be capable of providing images that have brighter highlights, greater contrast, and/or wider color gamuts than older displays. It can be desirable to take advantage of these improved capabilities without departing significantly from the creative intent embodied in the content being viewed.
It may be desirable to play video content created to take advantage of high-performance displays on legacy displays or displays that have lower capabilities. It would be desirable to provide methods and apparatus for adapting the appearance of video and other images displayed on different displays to preserve as much as possible a creative intent embodied in the image data.
The perception of color and luminance can be affected by ambient conditions. Video or other images presented under theater conditions (low ambient lighting) may be perceived by viewers significantly differently than the same video or other images would be perceived when viewed under conditions with significant ambient light. Further, the characteristics (such as the color temperature) of ambient light can affect a viewer's perception of video content. It would be desirable to display video or other images taking into account the environment in which the content is being viewed to preserve as much as possible a creative intent embodied in the video or other images.
There is a need to provide viewers of images (including still and/or video images) with viewing experiences that exploit the capabilities of displays on which they view the images. There remains a need for apparatus and methods which may be applied to adjust image data such that video or other image content encoded in the image data has a desired appearance when played.